The present invention relates to a substantially rotationally symmetrical anchoring element intended for implantation in tissue, for supporting prostheses or the like, to apparatus including such an anchoring element, to an anchoring assembly comprising such anchoring elements and to a method of fixing such anchoring elements in tissue.
In a first aspect the invention relates to a rotationally symmetrical anchoring element for holding prostheses, artificial joint components or the like, said anchoring element consisting of a tissue compatible material, the anchoring element being provided with an external screw thread extending from an insertion end thereof towards an opposite, application end.
Such anchoring elements in the form of screws are known and described in, for instance, U.S. Pat. No. 5,064,425. Such anchoring elements have also been marketed by NobelPharma AB for a long time with great success, mainly within the dental field, under the trademark Branemark System.RTM.. As a rule, such anchoring elements consist of titanium and are provided with a micropitted and/or macropitted surface for achieving optimal osseointegration with surrounding bone tissue. Examples for such surface treatments are described in, for instance, U.S. Pat. No. 4330891.
Very often, and particularly in dental applications, these screws experience mainly axial loads applied by artificial teeth or dental bridges supported by the anchoring elements via suitable spacer elements.
More recently such anchoring elements in the form of screws have also been used for anchoring fixtures for, for example, artificial hip joint, ankle joint and hand joint constructions. U.S. Pat. No. 5,041,139 and U.S. Pat. No. 5,108,444 disclose arrangements in which such anchoring screws are anchored in bones perpendicular to the longitudinal direction of the bone.